Is your soil ready for your plants? This is a great question and most of us might just look at the soil to say yes — it looks loamy and has that black, rich color, or no — it looks like red Virginia clay to me! There is so much more to soil than meets the eye, and I want to introduce the best way to know more about what is in your dirt: the soil test.
Before going on about soil tests, one note about using native plants. You can look up what plants are native to your county via the Flora of Virginia. Native plants, mostly, do not need changes in the soil if the plant matches up with the amount of sunlight it will get in the spot you want to put it – full sun to full shade or something in-between, and how wet the soil is after rain – wet to damp to dry. There are some exceptions, like blueberries that love acidic soil and plants adapted to the limestone/alkaline areas, but generally, put native plants right into native soils.
Maybe you heard some of these quotes about gardening, “just add Epsom salts for perfect tomatoes,” or “give your soil a boost with gypsum.” The intention of this advice might be good, but without a soil test, you won’t know if you are doing something beneficial or potentially harmful!
Epsom salts are magnesium sulfate, so this contains two necessary nutrients for plants: magnesium and sulfur. Both are necessary but only in very small amounts so if you are adding Epsom salts over many years, or several times a year in a growing season, you might exceed the optimum amount of magnesium and sulfur. Gypsum is calcium sulfate, so it contains necessary soil nutrients of calcium and sulfur, but again, without a soil test to know about a deficiency, adding gypsum over years could exceed the requirements of your plants. For more information about these and other soil myths, go to this article for a review of soil fertility..
So what is a soil test? This means you dig up some of the soil where you want to plant, say a vegetable garden. You are going to send that soil off for testing and then potentially make changes based on the soil test results. There are many companies that offer soil testing, and as part of its mandate, Virginia Cooperative Extension offers soil testing through Virginia Tech’s soil laboratory. You can pick up soil test kits and more information at your local VCE office and your Extension Master Gardener Help Desk or Help Line can also help interpret results!
How do you take a soil sample? To start, decide what area you want to test, you could test an existing garden or lawn, or a place where you’d like to start a new garden. Let’s say I’m concerned that I saw some yellowed leaves in my garden patch last year, so before I plant this year’s garden, I want to test the soil for any nutrient deficiencies.
First, I am going to get out a clean shovel and container – like a bucket. I am going to dig a shovel full of soil in one spot, add it to the bucket. I am going to repeat that 4-5 times throughout the garden, mixing each new shovel of soil into what is already in the bucket to get a uniform mix. If the soil is wet, make sure to put the bucket or container in the soil to let it dry out. You do not want a wet sample to send to the lab! Once the soil is dry, I am going to fill the box for the soil test lab, fill out the paperwork, and send it off – Virginia Cooperative Extension Offices around the state can help with this step. If you are doing a sample that has turfgrass or lawn, here is a great, short video from the Northern Virginia Master Gardeners to help you get a soil sample. Once you have the results back, you can amend the soil or not, after you see what the soil test recommends.
Happy Gardening!
Robyn
